French Pat. No. 2,381,303 filed Feb. 12, 1977 describes an apparatus which basically comprises an upper sample-melting unit and a lower sample-preparing unit. The upper unit has an induction coil that is energized with high-frequency electricity and that surrounds a crucible in which the sample to be melted is held, normally mixed with a highly oxidizing material that serves to dilute and melt the sample. The lower unit primarily consists of a mold into which the fused material is poured from the upper unit to produce a casting that can then be tested. The melting crucible must be made of a noble metal such as platinum or a platinum alloy which is highly conductive and which will not react with the sample.
Since the noble metals used for the crucible are somewhat wettable by their contents, some of the sample is lost to the crucible. Thus when the fused sample is poured out, it does not have the same volume it originally had. As a result this type of sample preparation can only be used with test methods which do not need complete recovery of the sample after its fusion, as for example x-ray analyses. Such analysis methods as optical spetrometry cannot be used. Furthermore the extremely expensive platinum or platinum-gold alloy crucible has a relatively short service life, so sample preparation with it is quite expensive.